Conventional refuse or trash compactors, as found in well-equipped kitchens, generally consist of an esthetically pleasing cabinet around a rigid frame designed to allow a power-driven ram to crush and compact refuse contained in a plastic bag supported in a removeable drawer. A convenient and sturdy drive for the ram comprises an electric motor driving one or more threaded power screws which generate controlled downward refuse-compacting forces when turned one way and then reverse direction to lift the ram to permit the drawer to be removed or additional refuse to be deposited within the drawer.
One example of a trash compactor utilizing a single threaded screw to drive the ram is disclosed in U.S. Pat. No. 3,817,352, titled "Lubricating Means for Trash Compactor Ram", in which a single power screw is completely enclosed within a moveable ram and is therefore inherently protected from contact with contaminants such as bits of refuse, especially strings and strips of material that could otherwise become entangled with the screw and hinder its proper operation.
U.S. Pat. No. 3,786,744, titled "Refuse Compactor Support Structure", to Miller et al. and U.S. Pat. No. 3,800,694, titled "Means for Mounting Components of a Refuse Compactor in Coordinated Relationship", to Miller et al, both of which are owned by the assignee hereof, disclose details, respectively, of a suitable frame structure and a typical two power screw driven ram type trash compactor. Specifically, this type of trash compactor has two long power screws vertically aligned, one inside each side of the cabinet, in a manner that permits a single pinion and chain drive to cause both screws to turn simultaneously in the same direction to provide, via threaded-on power nuts at the ram, two essentially parallel forces on the ram either in an upward direction or, by reversal of the drive motor direction, in the opposite direction. The ram is normally maintained in its uppermost position so that refuse may be deposited into a refuse bag contained in the removeable drawer position underneath.
Periodically, the user operates a switch that causes the ram to be driven down by the power screws so that it crushes the trash contained within the refuse bag in the drawer below. If there is insufficient trash the ram is stopped by a cross rail and a load responsive motor switch operates to reverse the direction of rotation of the power screws so that the ram automatically returns to its uppermost position. However, as more and more refuse is compacted within the drawer the ram travels downward by correspondingly smaller distances, until there is sufficient compacted refuse to permit removal of the bag. During each actuation of the ram by a user, following deposit of additional refuse to be compacted, the drive motor rotation is reversed by the load responsive switch when a predetermined degree of compaction is achieved. It is generally during this phase of the operation of the apparatus that assorted elements of the refuse, particularly bits of string, strips of paper and plastic, and the like, have a tendency to hang over the drawer edge and may occasionally become entangled with the threads of the power screws on either side. As glass bottles, cans and bottle caps are compacted, small, sharp, hard or abrasive bits of dirt may contact the screw thread and adhere to it, eventually causing accelerated wear. Also, particularly on dry days, small pieces of paper and plastic from the refuse may tend to become electrostatically attracted to the grease on the power screws and may tend to drift over from the drawer and come into contact with the lubricated greasy power screw threads.
The net result of incidental encounters between elements of the refuse and the power screw threads that are exposed on either side of the drawer, as the refuse is being compacted, is an accumulation of undesirable dirt on the power screws that eventually interferes with silent well-lubricated coaction between the power screws and power nuts carried at the top part of the ram to obtain the desired motion. This is aggravated by a tendency for the lubrication to drift downward on the screws over time and accumulate on a portion of each screw below the bottom of the stroke of the ram. It is generally very difficult and inconvenient for the owner of such a trash compactor to reach in and clean the threads and relubricate them frequently enough for proper operation of the compactor over prolonged periods.
There is, therefore, a current need for apparatus that will insulate power threads in power-driven trash compactors from dirt and refuse and insure well-lubricated, silent and longlasting operation thereof.